Power converter mode transitioning method and apparatus

A method of transitioning a power converter between a switched mode of operation and a linear regulator mode of operation comprising:

• enabling a switched mode control loop during operation in linear regulator mode, said step of enabling further including releasing control of a first current control device by a linear regulator control loop, and continuing to regulate an output voltage by retaining control of a second current control device by said linear regulator control loop to prevent said output voltage from dropping below a set voltage;
• setting said switched mode control loop to regulate said output voltage to a slightly higher than desired voltage, said step of setting accomplished by modifying a reference voltage to said switched mode control loop;
• setting said linear regulator control loop to regulate said output voltage to a slightly lower than desired voltage, said step of setting accomplished by modifying a reference voltage to said linear regulator control loop;
• sensing by said switched mode control loop that said output voltage is below the desired regulation voltage;
• charging an integrator capacitor to increase an error voltage signal;
• increasing said output power in response to said error voltage signal;
• detecting a low output condition by said switched mode control loop and said linear mode control loop by determining an increase in said error voltage beyond the range of said output voltage provided by said linear regulator control loop;
• increasing said output voltage by said switched mode control loop in response to said step of detecting a low output condition;
• reducing the current flow through said second current control device by said linear regulator control loop in response to said step of detecting a low output condition;
• switching off said second current control device by said linear regulator control loop when said switched mode control loop has increased said output voltage above a modified set point;
• alerting a mode controller by said linear regulator control loop by sending a signal indicating that the current through said second current control device has dropped to zero;
• shutting down said linear regulator control loop by said mode controller;
• passing control to said switched mode control loop by said mode controller;
• and
• regulating said output voltage by said switched mode control loop to a desired output voltage.

A power converter, comprising:

• a first current control device that receives an input signal;
• a second current control device that receives said input signal, said second current control device coupled to said first current control device;
• a linear regulator controller coupled to said first current control device by a first control signal and coupled to said second current control device by a second control signal;
• said first current control device and said second current control device cooperating to produce an output signal in response to said first and second control signals;
• a third current control device coupled to said first current control device;
• a switched mode controller coupled to said first current control device by a third control signal and coupled to said third current control device by a fourth control signal;
• said first current control device and said third current control device cooperating to produce said output signal in response to said third and fourth control signals;
• a converter mode controller controllably coupled to said linear regulator controller and said switched mode controller;
• said converter mode controller causing said power converter to operate in a switched mode in response to a plurality of circuit parameters being set to a first state, to operate in a linear regulation mode in response to one or more transition triggers, and to operate in one or more intermediate modes of operation during a transition between said linear regulation mode and said switched mode, wherein said converter mode controller prevents said output signal from exceeding a predetermined voltage ripple value by maintaining power converter operation in only one of said switched mode or said linear regulator mode in response to steady state input and output conditions.

A method of transitioning a power converter between a switched mode of operation and a linear regulator mode of operation, comprising the steps of:

• operating the power converter in a linear regulator operating mode, said linear regulator operating mode using a first current control device and a second current control device, wherein said first current control device and said second current control device cooperate to produce an output signal;
• operating the power converter in a switched mode operating mode, said switched mode operating mode using said first current control device and a third current control device, wherein said first current control device and said third current control device cooperate to produce said output signal;
• and
• varying a resistance across said first current control device and said second current control device such that power converter operation is maintained in only one of said switched mode operating mode and said linear regulator operating mode in response to steady state input and output conditions.

A method of transitioning a power converter between a switched mode of operation and a linear regulator mode of operation, comprising the steps of:

• operating the power converter in a switched mode operating mode using a switched mode control loop, said switched mode control loop acting to produce an output signal regulated to a desired switched mode output value;
• operating the power converter in a linear regulator operating mode using a linear regulator control loop, said linear regulator control loop acting to produce said output signal regulated to a linear regulator output value, said switched mode output value being greater than said linear regulator output value;
• and
• operating the power converter in a transitional operating mode in which both of said switched mode control loop and said linear regulator control loop cooperate to produce said output signal when said output signal is less than either of said switched mode or linear regulator output values.